Data storage/memory devices are one of many components of modern computers. Examples of data storage devices include hard disk drives (HDDs), which are electromechanical devices containing spinning discs and movable read/write heads, solid state drives (SSDs) with no moving parts, and hybrid drives, which combine features of HDDs and SSDs in one unit. Data storage/memory devices are also present in many additional devices, such as table computers, smart phones, and the like.
In data storage devices, especially HDDs, and in hardware such as servo application specific integrated circuits (ASICs) and printed circuit board assemblies (PCBAs), peak current levels in relation to average current levels present challenges to a host power supply in several ways. First, the ratio of peak current to average current drawn by, for example, a HDD coupled to draw power from a host, is often 4:1 or higher. This ratio may cause the host power supply design to be difficult. For example, designing for peak current may result in excess costs and unnecessary components, while designing for average current may not allow enough current to be available for device operation. If the power supply must provide sufficient current for all situations, then significant additional costs may be incurred in the design.
Second, the slew rate for changing currents is high, which can cause high frequency harmonics in the power distribution system for the storage device. This can potentially cause inductive losses in the storage device to become an issue, especially in server racks during spin-up of a HDD. As with peak to average current ratios, a high slew rate can complicate design of power distribution systems.